The invention relates to universal joints and, more particularly, to a telescopic tripod universal joint.
Tripod constant velocity universal joints have been used by the transportation industry for numerous years. A typical tripod joint is shown in U.S. Pat. No. 4,773,890 issued to Iwasaki et.al. on Sep. 27, 1988.
This joint consists of an outer race formed with three longitudinal chambers. A spider assembly is disposed within each chamber. Journaled on each of the spider trunnions is a roller. Interposed between each roller and the respective trunnion is a plurality of needle roller bearings.
While this joint has proven to be an effective design, it has several disadvantages. One disadvantage is during operation of the tripod joint at angle, the joint produces a third order axial cyclic vibration known as "shudder". This shudder phenomenon often times is felt by the driver and passengers of the vehicle.
Shudder is caused by sliding rather than rolling of the rollers when the joint is rotating at an angle. While at an angle, the plane of rotation of each roller is skewed relative to its respective outer race track. This causes a combination of rolling and sliding of the roller on its respective track as the spider moves axially relative to the outer race. This sliding action is the main component producing the third order axial cyclic vibration or shudder. As the angle of the joint increases, there is more sliding and therefore a higher axial load is induced.
There are numerous designs which attempt to minimize the axially induced force. Iwasaki et al. patent attempts to reduce this induced load by using angular contact on the tracks. This has the effect of lowering the surface area of contact between the roller and the track. While some reduction in load is possible with this joint, it does not significantly reduce the shudder phenomenon.
U.S. Pat. No. 4,619,628 issued to Orain on Oct. 28, 1986 illustrates a triplan joint which separates the components within the joint which are responsible for angular and translational movement. While this device is able to significantly reduce or even eliminate the axially induced forces in the joint, the design of the joint is complicated and expensive.
Various other patents have approached the problem by going to multiple piece roller assemblies in an attempt to reduce the "shudder" phenomenon.
U.S. Pat. No. 4,954,119 issued to Sasaki et al. on Sep. 4, 1990; U.S. Pat. No. 4,891,035 issued to Sasaki et al. on Jan. 2, 1990; U.S. Pat. No. 4,854,917 issued to Mizukoshi on Aug. 8, 1989; U.S. Pat. No. 4,786,270 issued to Iwasaki on Nov. 22, 1988; U.S. Pat. No. 4,747,803 issued to Kimata et al. on May 31, 1988; U.S. Pat. No. 4,578,048 issued to Hirai et al. on Mar. 25, 1986 and U.S. Pat. No. 4,379,706 issued to Otsuka et al. on Apr. 12, 1983 all illustrate different designs of multi-component roller design.
The capability of the above enumerated tripod joints to reduce the axially induced load lies somewhere between a typical tripod as shown in Iwasaki et al. and a triplan joint as shown in Orain. While these joints all reduce the axially induced load, they all are relatively expensive due to the design of their complicated multi-component roller assembly.
Accordingly, it is desirous to have a multi-component roller assembly which reduces the axially induced loads and is relatively inexpensive and reliable.